CognitiveClouds React Js Frontend Developer Interview Questions and Answers

Q1. 1) State and props 2) Basic JS question
Add your answer

Q1. What is throttling?
Ans. 
Throttling is a technique used to control the rate at which a function is executed.
• Throttling limits the number of times a function can be called over a specified time period.

• It helps in optimizing performance by preventing excessive function calls, especially in scenarios like scroll events or API requests.

• Example: Limiting the number of API calls to a server to prevent overwhelming the server with too many requests.
Answered by AI
Add your answer

Q1. Way of copy a object
Ans. 
Use the spread operator or Object.assign() method to copy an object in JavaScript.
• Use the spread operator: const newObj = { ...oldObj };

• Use Object.assign() method: const newObj = Object.assign({}, oldObj);
Answered by AI
Add your answer

Q1. What is HOC in react?
Ans. 
HOC stands for Higher Order Component. It is a pattern in React that allows reusing component logic.
• HOC is a function that takes a component and returns a new component with additional functionality.

• It helps in code reuse, logic abstraction, and cross-cutting concerns.

• HOCs can be used for tasks like authentication, logging, and data fetching.

• Example: withAuth HOC can add authentication logic to a component.

• HOCs can be
Answered by AI
Add your answer
Q2. How does React work?
Ans. 
React is a JavaScript library for building user interfaces that uses a virtual DOM and a component-based architecture.
• React uses a virtual DOM to efficiently update the user interface.

• It follows a component-based architecture where UI is divided into reusable components.

• React uses a declarative syntax to describe how the UI should look based on the application state.

• It efficiently updates only the necessary parts of th...read more
Answered by AI
Add your answer

Q1. Frontend developer
Add your answer

Html, CSS, bootstrap, JavaScript, react.js

Q1. Questions based on the skills and position you are applying for
Add your answer

Q1. Related to the positions and your skillsets which you mentioned in your resume
Add your answer

Q1. Salary Discussion and your location preference
Add your answer

Basic coding nd programming and moderate level

Q1. What is usestate () in react js ?
Ans. 
useState() is a React Hook that allows functional components to manage state.
• useState() is imported from React: `import React, { useState } from 'react';`

• It returns an array with two elements: the current state and a function to update it.

• Example: `const [count, setCount] = useState(0);` initializes count to 0.

• The state can be updated by calling the updater function: `setCount(count + 1);`.

• useState() can hold any data
Answered by AI
Add your answer
Q2. What are the advantages of react js?
Ans. 
React JS offers a component-based architecture, efficient rendering, and a strong community, making it ideal for modern web development.
• Component-Based Architecture: React allows developers to build encapsulated components that manage their own state, making code reusable and easier to maintain.

• Virtual DOM: React uses a virtual representation of the DOM to optimize rendering, resulting in faster updates and improved pe...read more
Answered by AI
Add your answer
Q3. What are the limitations of React jd?
Ans. 
React JS has limitations such as performance issues, SEO challenges, and a steep learning curve for beginners.
• Performance: Large applications can lead to performance bottlenecks if not optimized properly. For example, excessive re-renders can slow down the app.

• SEO Challenges: React applications can have issues with search engine optimization since content is rendered on the client-side. Server-side rendering (SSR) can ...read more
Answered by AI
Add your answer
Q4. What are the Keys in React?
Ans. 
Keys in React are unique identifiers for elements in lists, helping React optimize rendering and manage component updates efficiently.
• Keys help React identify which items have changed, are added, or are removed.

• They should be unique among siblings but can be reused in different lists.

• Using indexes as keys can lead to issues with component state and performance.

• Example: <li key={item.id}>{item.name}</li> in
Answered by AI
Add your answer
Q5. What is JSX?
Ans. 
JSX is a syntax extension for JavaScript that allows writing HTML-like code within JavaScript, primarily used in React.
• JSX stands for JavaScript XML.

• It allows developers to write HTML structures in the same file as JavaScript code.

• JSX is transpiled to JavaScript using tools like Babel.

• Example: <h1>Hello, World!</h1> becomes React.createElement('h1', null, 'Hello, World!').

• JSX can also embed JavaScript expre...read more
Answered by AI
Add your answer
Q6. What are the differences between functional and class components
Ans. 
Functional components are simpler and use hooks, while class components manage state and lifecycle methods.
• Functional components are stateless and simpler, while class components can manage state and lifecycle methods.

• Functional components use hooks (e.g., useState, useEffect) for state and side effects, whereas class components use 'this.state' and 'this.setState'.

• Class components require 'render()' method to return J...read more
Answered by AI
Add your answer